NN. SPLANCHNIC!. 395 



intervening nerves and give rise to nervous branches wliicli are distributed to the viscera 

 and blood vessels. Besides the chain of ganglia, the sympathic nerves may have ganglia 

 developed upon them at almost any point in their course. The various parts of the sym- 

 pathic are intimately associated with each other and also with the cerebro-spinal nervous 

 system. So close is this connection that some authors consider the sympathic as belong- 

 ing to the peripheral part of the cerebro-spinal system (Quain, A, I, 519). 



There are nominally as many pairs of sympathic ganglia as vertebrge, except in the 

 cervical region and rarely also in other regions. From each ganglion passes a branch to 

 the corresponding spinal nerve (Fig. 107, 109). 



§ 1043. Specimen, Preparation and Dissection. — The same 

 specimen may be employed as for tlie vagus, and it should be pre- 

 pared in precisely the same manner (§ 1030). The exposure is also 

 the same, and the method of dissecting the nerves (§ 1031). 



Nearly dorsad of the ganglion of the root of the vagus is the 

 similar, fusiform, superior cervical ganglion of the sympathic. It 

 may be carefully isolated ; then, by carefully tearing the sheath of 

 the combined vagus and sympathic, the two may be separated in 

 the neck. About 1 cm. from the 1st rib the sympathic inclines lat- 

 erad, and very near it there appears in most subjects a small gan- 

 glion, the thyroid or middle cervical ganglion (Fig. 107, Ong. 

 thyr.., Fig. 108). Pull the nerve, and it will be found to divide 

 into two parts, one of which passes dorsad and the other ventrad of 

 the A. suhclama (Fig. 109). Cut the axillary artery and turn it 

 mesad. The two nerves may then be followed to their termination 

 in the ganglion vertebrale or the inferior cervical ganglion just 

 caudad of the 1st rib (Fig. 107, Gng. vert., 108, 109). Pull upon the 

 nerve and make out the branches passing from this ganglion. They 

 are shown in Fig. 107, 108 and 109. After tliese branches are 

 traced, tear away the pleura and follow the sympathic chain along 

 the thorax. Note that there is a ganglion for each vertebra, and 

 that eacli ganglion communicates with the corresponding spinal 

 nerve (Fig. 107). 



§ 1044. NN. splanchnici. — The sympathic ganglion about oppo- 

 site the last rib is somewhat larger than those preceding it, and there 

 is given off a branch, the N. splanchnicus major, which passes 

 caudad and slightly ventrad and penetrates the diaphragm. The 

 diaphragm should be cut, the abdomen well opened and the viscera 

 turned to the right ; then by pulling upon this nerve it will be seen 

 to move the semilunar ganglion, showing that it joins that body. 

 Now follow the sympathic from the origin of the great splanchnic. 

 It becomes more nearly mesal in position, and when near the dia- 



